The league’s Disciplinary Committee made the announcement following days of deliberation and review on the incident, which left Zakuani in a Denver hospital and the veteran Mullan absent from workouts and, according to Rapids head coach Gary Smith, “visibly shaken.”

Mullan faces an automatic one-game suspension for the red card he received following the tackle, bringing the total games missed to 10. It is the largest suspension handed down for an on-the-ball tackle in league history.

He also faces a $5,000 fine, as well as a $250 fine for receiving a red card.

"The Committee felt the egregious nature of the foul and the severity of the injury warranted the discipline issued," executive vice president of competition and game operations Nelson Rodriguez said in a statement. "The Committee believes the challenge showed an utter disregard for Zakuani's safety.

"In making this decision, the Committee took several factors into account: the timing of the challenge, the location on the field, the moments immediately before the challenge where it is clear that Mullan is frustrated and the severity of Zakuani's injury"

The MLS Players' Union will not appeal the decision.

The suspension is the largest handed out by the league since former Houston Dynamo midfielder Ricardo Clark was suspended a total of 10 games and fined $10,000 after he kicked former FC Dallas and current Philadelphia Union striker Carlos Ruiz during a match in 2007.

The Zakuani incident occurred in the early moments of Seattle’s 1-0 win over the Rapids last Friday night at Dick’s Sporting Goods Park in Commerce City, Colo. Mullan, appearing to be upset about a non-call against the Sounders’ Tyson Wahl just seconds earlier, came in hard with a right-footed tackle on Zakuani as the Seattle midfielder moved upfield with the ball just in front of the Colorado bench.

Zakuani buckled to the turf and quickly pointed to his right leg while some surrounding Sounders players – and Rapids players on the nearby bench – steered their eyes away from what was clearly a serious injury.

“Before this season, MLS worked with all its players, coaches, referees and the two federations to develop, illustrate and discuss several key points of emphasis," Rodriguez said. "One of those points of emphasis is to protect the safety of the player on the ball and reduce or eliminate reckless and violent tackles. Mullan’s tackle is the type of play we need to eliminate from our game and the level of discipline is consistent with our efforts to do so."

Mullan is eligible to return to MLS play on June 26, when the Rapids travel to meet the Columbus Crew.

“I’m sorry for Steve,” Mullan told the Rapids’ web site after the game. “It was never my intention to injure him in the least. It was a tackle that I’ve done hundreds of times, and I’d probably do it again.

“I had no intention of hurting him,” Mullan added. “It was a freak thing. I apologize and wish him a speedy recovery.”

Mullan also released an official apology through the sports management firm James Grant Sports Ltd. on Wednesday.

"It is with regret that my tackle resulted in the injury of Steve and I am deeply sorry to Steve and all those impacted by his injury,” Mullan said in the statement.

Mullan did not report to Rapids practice on Tuesday, and Smith told reporters that Mullan was “distraught” in the aftermath of the incident. Smith also said that Mullan has inquired about receiving psychological counseling to deal with the incident.

The red card and suspension are a rarity for Mullan, a league veteran and the only five-time MLS Cup winner currently playing in the league. Prior to the incident last week, he had not received a red card since his days with the Houston Dynamo in 2006, and he has been sent off four times in 263 career regular-season games.

Zakuani, meanwhile, is still recovering at the Rose Medical Center in Denver after undergoing surgery late last Friday night. Although the timeline for his recovery has not been officially released, Zakuani is expected to miss the duration of the season.

He issued a letter to fans in the days following the incident, saying that he “can't thank my family, friends and fans enough for their love towards me.”

“After 24 hours, I had received about 400 e-mails, a couple hundred Facebook messages, hundreds of Facebook wall posts, 62 text messages and several phone calls from all over the world,” Zakuani said in the letter. “Thank you for your love, thoughts and prayers toward me.”

Statement from Adrian Hanauer, Sounders FC General Manager

“In situations such as this, the game is robbed of its brilliance. Steve Zakuani is a young, talented and highly entertaining player. He will be missed, and we all wish him a full and speedy recovery.

“As a league, the Commissioner has stated his intention to be more protective of dynamic, attacking players. Hopefully this suspension is a step in the right direction.

“However, the harsh reality of this situation is that no length of suspension will bring back Steve to action any faster.”